The present invention relates to a silver halide photographic material. More particularly, the present invention relates to a high speed silver halide photographic material utilizing the technique of dopants.
As one of the techniques of modifying silver halide grains to bring about as much improvement as is expected in the properties of a silver halide photographic material as a whole, there is known a technique of incorporating a substance (dopant) other than silver and halide ions into silver halide grains. This technique is referred to as xe2x80x9ca doping techniquexe2x80x9d. In particular, many researches on the technique of doping transition metal ions have been made. As a result, it is generally recognized that the transition metal ions incorporated as a dopant into silver halide grains can effectively modify photographic properties even when the amount thereof is minute.
Besides the technique of doping transition metal ions, there is known the technique of doping silver halide grains with transition metal complexes having cyanide ions as ligands to heighten the sensitivity of silver halide emulsions. In particular, many disclosures have been made about the emulsions having sensitivities increased by doping with the hexacyano complexes containing the group VIII metals. As the dopants containing cyanide ions, for instance, a hexacyanoferrate (II) complex and a hexacyanoferrate (III) complex are disclosed in JP-B-48-35373 (The term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d). However, the invention cited above regards the sensitivity increasing effect as being limited to the cases of complexes containing iron ion and having no relation to the species of ligands. Many other cases are known where high sensitivity can be conferred on emulsions by doping them with hexacyanoferrate (II) complexes. Such cases are disclosed, e.g., in JP-A-5-66511 (The term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) and U.S. Pat. No. 5,132,203. There are also known the emulsions which are doped with cyano-complexes of metals other than iron to obtain high sensitivity. For instance, JP-A-2-20853 discloses that silver halide emulsions can acquire high sensitivity by comprising silver iodochloride doped with a rhenium, ruthenium, osmium or iridium complex. Many of other metal complexes are also used as dopant, and can produce not only the sensitivity increasing effect but also various effects, such as an improvement in reciprocity failure and an increase in contrast. For instance, U.S. Pat. No. 2,448,060 discloses the emulsions sensitized by doping them with a platinum (II) or palladium (IV) complex having halogen ions as ligands. And U.S. Pat. No. 3,790,390 discloses the emulsions doped with cyano-cobalt (III) complexes in addition to the emulsions doped with cyano-iron (II) or cyano-iron (III) complexes, wherein spectral sensitizing dyes are also contained. Further, the silver halide grains formed in the presence of a rhodium (III) complex containing 3, 4, 5 or 6 cyanide ions as ligands are disclosed in U.S. Pat. No. 4,847,191. Those patent prove that the high intensity failure can be diminished by dopants. In European Patents 0335425 and 0336426 and JP-A-2-20854 are disclosed the silver halide emulsions doped with rhenium, ruthenium, osmium or iridium complexes having at least 4 cyano-ligands. Therein, it is described that the doped emulsions are improved in storage stabilities of sensitivity and gradation and reduced in low intensity failure. European Patent 0336427 and JP-A-2-20852 disclose the silver halide emulsions respectively using vanadium, chromium, manganese, iron, ruthenium, osmium, rhenium and iridium complexes having the octahedrasl structure with nitrosyl or thionitrosyl ligands, wherein the low intensity reciprocity failure is improved without attended by lowering of medium illumination sensitivity. As the dopants other than transition metal ions, the emulsions doped with bismuth or lead ions are disclosed in U.S. Pat. No. 3,690,888, and the emulsions containing the group XIII or XIV metal ions are disclosed in JP-A-7-128778.
With respect to the ligands of complexes used as dopant, the cyanide ions are regarded as most popular, but halide ions are also used frequently. As examples of a dopant having the structure of [MCl6]nxe2x88x92 wherein M is a metal, mention may be made of the hexachlororuthenium, hexachloroiridium and hexachlororhenium complexes disclosed, e.g., in JP-A-63-184740, JP-A-1-285941, JP-A-2-20852 and JP-A-2-20855. Further the octahedral rhenium complexes having halogeno, nitrosyl, thionitrosyl, cyano, aquo or/and thiocyano ligands are disclosed as dopants in European Patent 0336689 and JP-A-2-20855. In addition, the emulsion containing a octahedral transition metal complex having one carbonyl ligand and the emulsion containing a octahedral transition metal complex having two oxo ligands are disclosed as those having useful photographic properties in JP-A-3-118535 and JP-A-3-118536, respectively.
In recent years, techniques involving the doping of silver halide grains with complexes having an organic compound as a ligand for the purpose of modifying the properties of emulsion have been studied. U.S. Pat. Nos. 5,360,712, 5,457,021 and 5,462,849, European Patent (EP) 0709724, JP-A-7-72569 and JP-A-8-179452 disclose examples of the use of many complexes comprising organic compounds as ligands. It is described that emulsions comprising silver halide grains doped with [(NC)5Fe(xcexc-4,4xe2x80x2-bipyridine) Fe(CN)5]6xe2x88x92 in particular have a remarkably raised sensitivity. JP-A-11-24194 discloses that emulsions having a high sensitivity and improved reciprocity failure is obtained by doping with [Fe(CO)4(P(Ph)3)]0  or [Fe(CO)3(P(Ph)2)]0. Further, JP-A-11-102042 discloses that [M(CN)5L]""xe2x88x92 (wherein M represents Fe2+, Ru2+ or Ir""+), [Fe(CO)4L]0, [Mxe2x80x2(CN)3L]xe2x88x92 (wherein Mxe2x80x2 represents PD2+ or Pt2+) and [IrCl5L]2xe2x88x92 type complexes wherein L is 2-mercapto-benzimidazole, 5, methyl-s-triazolo(1.5-A)pyrimidine-7-ol or 2-mercapto-1,3,4-oxadiazole can provide high speed emulsions. Moreover, JP-A-10-293377 discloses that emulsions doped with [RuCl5Lxe2x80x2]2xe2x88x92 (wherein Lxe2x80x2 represents imidazole, benzimidazole or derivative thereof) provide an extremely increased contrast at which the resulting sensitivity is far higher than that of emulsions doped with the conventional desensitized high contrast dopants.
When the octahedral complexes coordinated with six ligands are incorporated as dopants into silver halide grains, as described in references, including J. Phys.: Condens. Matter, 9 (1997) 3227-3240, literatures and patents, the [AgX6]5xe2x88x92 unit (X=halogen ion) in silver halide grains is replaced by the complex molecules so that the central metal (ion) occupies the lattice position of Ag+ ion and the ligands occupy the lattice position of halide ions. Accordingly, U.S. Pat. No. 5,360,712 discloses that the complex to be used as a dopant must be occupied in the coordination site of central metal (ion) by halogen or pseudo-halogen ions in a proportion of half or more and the organic compound which can be used as a ligand must have a proper molecular size with respect to the size of the space in the crystal lattice as a host.
On the other hand, U.S. Pat. No. 3,672,901, JP-A-2-259749 and JP-A-336537 disclose examples of the use of, as a dopant, a complex comprising no halogen or pseudo-halogen ions bonded thereto at the coordination sites of metal ion such as [Fe(ETDA)]2xe2x88x92 (wherein EDTA represents ethylenediamine tetraacetic acid) and [Ir(C2O4)3]3xe2x88x92. The above described U.S. Pat. No. 5,360,712 discloses that these dopants have no large effect. According to this patent, these complexes have all coordination sites occupied by an organic compound and thus cannot have halogen or pseudo-halogen ions required to take themselves into silver halide grains and are not appropriate as dopant.
As described above, complexes having an organic compound as ligand which have heretofore been used as dopant each have as ligand an organic compound occupying only one or two of the six coordination sites of central metal (ion). There have been known no examples of the use of complexes each having greater than half or all of the coordination sites occupied by an organic compound, particularly dopants containing ligands having no electric charge and having no sites interact with other metal ions on the surface of complex molecules, and the resulting modification of photographic properties.
In order that the emulsions acquire high speed, they are required to undergo chemical sensitization besides the addition of dopants. In the case where the emulsion doped with a cyano-complex is subjected to gold sensitization as typical of chemical sensitization, as described, e.g., in JP-A-8-62761, the cyanide ions liberated from the complex are adsorbed to the silver halide grain surface and form a cyano-gold complex together with the gold ion added as a gold sensitizer, thereby inhibiting the formation of sensitized center by the gold sensitizer. In order to effect gold sensitization of the emulsion containing a cyano-complex as dopant, it is required to keep the cyano groups away from the silver halide grain surface, e.g., by making the cyano-complex dope the sub-surface of silver halide grains as described in U.S. Pat. No. 5,132,203 and European Patent 0508910. As another preventive against the inhibition of gold sensitization, there is known the method of adding zinc ion or the like as disclosed in JP-A-6-308653. As mentioned above, a further measure must be taken in order to achieve both the increase of photographic speed by the dopant which has heretofore relied on cyano complex and the gold sensitization.
Most of the dopants hitherto known to enable the increase of photographic speed are complexes having cyanide ions as ligands. These cyano-complexes still have a toxicity problem common to cyan compounds even if their problem of inhibiting gold sensitization can be overcome. Therefore, new dopants containing no cyanide ions and capable of imparting high speed to emulsions have been awaited.
An object of the present invention is to provide a silver halide photographic material containing no cyanide ions but having a higher photographic speed than ever.
The foregoing object of the present invention will become apparent from the following detailed description and examples.
The foregoing object of the present invention is attained by a silver halide photographic material according to any of the following item (1) and the following items (2) to (12) which are preferred embodiments:
(1) A silver halide photographic material comprising a support having thereon at least one silver halide emulsion layer, wherein there is contained a complex in which an organic compound having no electric charge which doesn""t coordinate with a metal or a metal ion other than the central metals or metal ions occupies more than half of the central metals or metal ions as coordination site.
(2) The silver halide photographic material according to the foregoing item (1), wherein the silver halide grains contained in the emulsion contain a complex in which an organic compound having no electric charge which doesn""t coordinate with a metal or a metal ion other than the central metals or metal ions occupies more than half of the central metals or metal ions as coordination site.
(3) The silver halide photographic material according to the foregoing item (1) or (2), wherein the silver halide grains contained in the silver halide emulsion contain a metal complex represented by the following formula I or II:
[MLnX(6xe2x88x922n)]M+xe2x80x83xe2x80x83(I) 
[ML[(6xe2x88x923iX1/3)]Lxe2x80x2iX[(6xe2x88x923iX1/3)]]j+xe2x80x83xe2x80x83(II) 
xe2x80x83wherein M represents an arbitrary metal or metal ion; L represents an organic bidentate ligant coordinated to a metal or a metal ion (i.e., an organic compound which is coordinated to a metal or a metal ion at two donor sites of the ligand; Lxe2x80x2 represents an organic tridentate ligant coordinated to a metal or a metal ion (i.e., an organic compound which is coordinated to a metal or a metal ion at three donor sites of the ligand); X represents an arbitrary chemical species, with the proviso that a plurality of L""s, (Lxe2x80x2)""s and X""s, if contained in the same compound, may be the same or different compounds, respectively; n represents an integer of 2 or 3; i represents an integer of 1 or 2; and m and j each represent an integer of from xe2x88x924 to +5.
(4) The silver halide photographic material according to the foregoing item (3), wherein L in the formula I or II comprises 2,2xe2x80x2-bipyridine or 1,10-phenanthroline as a basic structure.
(5) The silver halide photographic material according to the foregoing item (3), wherein Lxe2x80x2 in the formula II comprises 2,2xe2x80x2:6xe2x80x2xe2x88x922xe2x80x3-terpyridine as a basic structure.
(6) The silver halide photographic material according to the foregoing item (1) or (2), wherein the silver halide grains contained in the emulsion contain a metal complex represented by the following formula III:
[MLxe2x80x3kX(6xe2x88x92k)]1+xe2x80x83xe2x80x83(III) 
xe2x80x83wherein M represents an arbitrary metal or metal ion; Lxe2x80x3 represents an organic compound which is a monodentate ligand coordinated to a metal or a metal ion; X represents an arbitrary chemical species, with the proviso that a plurality of (Lxe2x80x3)""s and X""s, if contained in the same compound, may be the same or different compounds, respectively; k represents an integer of 4 to 6; and 1 represents an integer of xe2x88x924 to +5.
(7) The silver halide photographic material according to the foregoing item (6), wherein Lxe2x80x3 in the formula III comprises a basic structure selected from the group consisting of furan ring, thiophenine ring, 2H-pyrrole ring, pyran ring and pyridine ring as a basic structure.
(8) The silver halide photographic material according to any one of the foregoing items (4) to (6), wherein M in the formulae I, II and III is a metal ion selected from the group consisting of magnesium ion, calcium ion, strontium ion, barium ion, iron ion, ruthenium ion, manganese ion, cobalt ion, rhodium ion, iridium ion, copper ion, nickel ion, palladium ion, platinum ion, gold ion, zinc ion, titanium ion, chromium ion, osmium ion, cadmium ion and mercury ion.
(9) The silver halide photographic material according to any one of the foregoing items (4) to (6), wherein M in the formulae I, II and III is a metal ion selected from the group consisting of iron ion, ruthenium ion, manganese ion, cobalt ion, rhodium ion, iridium ion, titanium ion, chromium ion, and osmium ion.
(10) The silver halide photographic material according to the foregoing item (9), wherein in the formulae I, M represents a metal ion selected from the group consisting of iron ion, ruthenium ion and cobalt ion, L represents 2,2-bipyridine or 1,10-phenanthroline, n represents an integer of 2 or 3 and m represents an integer of 2.
(11) The silver halide photographic material according to the foregoing item (9), wherein in the formulae II, M represents iron ion or ruthenium ion, L represents 2,2-bipyridine or 1,10-phenanthroline, Lxe2x80x2 represents 2,2xe2x80x2:6xe2x80x2-2xe2x80x3-terpyridine, i represents an integer of 1 or 2 and j represents an integer of 2.
(12) The silver halide photographic material according to the foregoing item (9), wherein in the formulae III, M represents iron ion or ruthenium ion, Lxe2x80x3 represents pyridine, k represents an integer of 6 and l represents an integer of 2.
As described, e.g., in Bulgarian Chem. Commun., 20 (1993) 350-368, Radiat. Eff. Defects Solids, 135 (1955) 101-104, and J. Phys.: Condens Matters, 9 (1977) 3227-3240, the hexacyano-complexes added for doping silver halide grains introduce shallow electron centers arising from the coulombic traps into the silver halide grains. In particular, when the complex contains a divalent metal ion, such as Fe2+ and Ru2+, as its central metal (ion), electron traps having an optimum depth arising from the coulombic field can be introduced into an atmosphere of grains formed by Ag+ and Clxe2x88x92 by an excess charge of +1 to elongate the time from the generation of photoelectrons by exposure to the deactivation thereof, thereby considerably increasing the photographic speed, as disclosed in ICPS, 1998, Final program and Proceedings, Vol. 1, p. 89, ICPS, 1998, Final program and Proceedings, Vol. 1, p. 92, and JP-A-8-286306. Therein, the cyanide ions which have been used as ligand become ligands essential to producing a strong ligand-field effect. In other words, electron is donated from metal to ligand (back-donation effect) to form xcfx80-bond that brings about further stabilization of t2g orbital, reduction of the bond distance between metal and ligand and increase of effective positive charge of metal ions resulting in an effect of drastically increasing the split of d orbital of metal. This effect causes the eg orbital in the complex (lowest unoccupied molecular orbital in the complex) with which the silver halide grains have been doped to have a higher energy than that of the bottom of the conduction band of silver halide, which has nothing to do with electron trapping. Only in this manner, shallow electron centers arising from the coulombic field can be formed in the vicinity of dopants.
It is generally known that heterocyclic compounds, particularly 1,10-phenanthroline or 2,2xe2x80x2-bipyridine, bring about a strong ligand-field effect close to cyano-complexes during complexing. It can be thought that by doping with these complexes the lowest unoccupied molecular orbital can be at a higher energy level than that of the bottom of the conduction band of silver halide similar to the hexacyano-complexes. Further, the use of a compound having no electric charge as ligand causes excess charge taking part in electron capture by coulombic center to be distributed not only on a metal but also on ligands. Taking into account the formation of silver nuclei in silver halide grains, it is thought that when photo-excited electrons move more freely in a wide range, silver nuclei can be formed efficiently, as in impurity band in semiconductors, In actuality, according to ENDOR""s experiment on an emulsion doped with hexacyanoferrate (II) described in J. Phys.: Condens Matters, 9 (1977) 3227-3240, the range of dopant concentration at which an electron signal regarded to be trapped by impurity band begins to be observed coincides with the range of dopant concentration at which a sensitivity increase clearly begins. The state of shallowly trapped electrons can be described by effective mass approximation and thus can be considered with hydrogenlike 1s model. It can thus be presumed that the greater the radius of the field by which these electrons are bound (radius of hydrogen atom model described by effective mass approximation) is, the greater is the resulting sensitivity rise. From this standpoint of view, the foregoing heterocyclic compounds are preferably used as ligand. On the other hand, it can be thought that in order to obtain proper shallow electron traps by dopants, the molecule used as dopant preferably has less electron distribution so that electrons cannot be localized in the electron traps. If there are other donor sites of hetero atoms or substituents besides donor sites to central metal inside the ligand, it is very likely that polarization can occur in the ligand. It is thus likely that these structures are not suitable for trapping of electrons by a uniformly mild constraint force. From this standpoint of view, as the dopant for providing high sensitivity there may be used an organic compound, particularly a complex having an aromatic compound or heterocyclic compound as ligand. In particular, taking into account the ligand-field effect, compounds which are coordinated to metal ions at two donor sites or three donor sites are desirable.
The term xe2x80x9corganic compound xe2x80x9d as used herein means a compound having a chain or cyclic hydrocarbon as a parent structure or a compound in which carbon or hydrogen atoms of a part of the parent structure are replaced by other atoms or atomic groups. Taking into account the magnitude of ligand-field effect as mentioned above, the organic compound is preferably an aromatic compound or heterocyclic compound. As such an aromatic compound there is preferably used a compound having a substituent which forms a coordination site on two adjacent carbon atoms. Examples of such an aromatic compound include verathol, catechol, (+/xe2x88x92)-hydrobenzoin, 1,2-benzenedithiol, 2-aminophenol, o-anisidine, 1,2-phenylenediamine, 2-nitronaphthol, 2-nitroaniline, and 1,2-dinitrobenzene. Further, an aromatic compound which doesn""t have a substituent which forms a coordination site on two adjacent carbon atoms but has two coordination site-forming substituents which are located at a distance such that they can be coordinated to one metal. Specific examples of such an aromatic compound include benzyl, 1,8-dinitronaphthalene, and 1,8-naphthalenediol. These aromatic compounds are preferred examples of bidentate ligand L in the formula I. The heterocyclic compound coordinated at one-donor site preferably has an oxygen atom, sulfur atom, selenium atom, tellurium atom or nitrogen atom as hetero atom in its ligand. Also preferably, the heterocyclic compound has a phosphorus atom. The heterocyclic compound which is coordinated at two donor sites or three donor sites to metal or metal ion is preferably a ring-condensed heterocyclic compound in which these heterocyclic compounds coordinated at one-donor site are connected to each other. Specific examples of monodentate ligand Lxe2x80x3 in the formula III include furan, thiophenine, 2H-pyrrole, pyran, pyridine, and derivative thereof. The preferred bidentate ligand L in formula I is a compound in which the compound preferred as Lxe2x80x3 is connected, such as 2,2xe2x80x2-bithiophene, 2,2xe2x80x2-bipyridine and derivatives thereof. Further, a compound having a condensed ring connected to the basic structure of these bidentate ligands, such as 2,2xe2x80x2-biquinoline, 1,10-phenanthroline and derivative thereof is preferably used as bidentate ligand L in formula I. Specific preferred examples of Lxe2x80x2 in the formula II include 2,2xe2x80x2:5xe2x80x2,2xe2x80x3-terthiophene, 2,2xe2x80x2:5xe2x80x2,2xe2x80x3-terpyridine, and derivative thereof. As the substituent on these derivatives there may be preferably used one which doesn""t interact with metal ions. Even if these derivatives have a substituent which can be coordinated to metal, compounds which have a substituent having a donor atom coordinated to the central metal and thus form bi- or tri-dentate ligands as a whole, are preferably used. Specific preferred examples of these substituents include a hydrogen atom, substituted or unsubstituted alkyl groups (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, 2-ethylhexyl, dodecyl, hexadecyl, t-octyl, isodecyl, isostearyl, dodecyloxypropyl, trifluoromethyl), alkenyl groups, alkinyl groups, aralkyl groups, cycloalkyl groups (e.g., cyclohexyl, 4-t-butylcyclohexyl), substituted or unsubstituted aryl groups (e.g., phenyl, p-tolyl, p-anisyl, p-chlorophenyl-4-t-butylphenyl, 2,4-di-t-aminophenyl), halogen (e.g., fluorine, chlorine, bromine, iodine), cyano groups, mercapto groups, hydroxyl groups, alkoxy groups (e.g., methoxy, butoxy, methoxyethoxy, dodecyloxy, 2-ethylhexyloxy), aryloxy groups (e.g., phenoxy, p-tolyloxy, 4-t-butylphenoxy, alkylthio, arylthio, acyloxy, sulfonyloxy), substituted or unsubstituted amino groups (e.g., amino, methylamino, dimethylamino, anilino, N-methylanilino), and acyl groups (e.g., formyl, acetyl). The adjacent substituents in these molecules may be subjected to ring closure to form a saturated carbon ring, aromatic carbon ring or heteroaromatic ring. In the present invention, however, the ligand in the complex formed by these basic structure and substituents is limited to an organic compound which neither has electric charge nor interacts with metals or metal ions other than the central metal or metal ion even during complexing.
The central metal of the invention is not specifically limited. In practice, however, supposing that as described in many reference, including J. Phys.: Condens. Matter, 9 (1997) 3227-3240, and many patents, when the octahedral complexes (six-coordinated) are incorporated as dopants into silver halide grains, the [AgX6]5xe2x88x92 (Xxe2x88x92=halogen ion) in silver halide grains functions as a unit to enable partial replacement of the grains by the dopants, the metals capable of assuming either four-coordinated or six-coordinated structure around them are preferably used. It is more desirable that those metals or the ions thereof have no unpaired electron or, when the d-orbital of those metals are split by the ligand field, all the stabilized orbital thereof are filled with electrons. Specific preferred examples of such a central metal (ion) include alkaline earth metal ion, iron ion, ruthenium ion, manganese ion, cobalt ion, rhodium ion, iridium ion, copper ion, nickel ion, palladium ion, platinum ion, gold ion, zinc ion, titanium ion, chromium ion, osmium ion, cadmium ion, and mercury ion. Particularly preferred among these metal ions are iron ion, ruthenium ion, manganese ion, cobalt ion, rhodium ion, iridium ion, titanium ion, chromium ion, and osmium ion. Most preferably, iron ion, ruthenium ion, and cobalt ion are used.
Specific examples of the complexes according to the invention will be given below, but the present invention should not be construed as being limited thereto.
In the present invention, the doping complex molecule is a cation. As the anion with which the cation forms a salt there may be preferably used one which can be easily dissolved in water to facilitate the precipitation of silver halide emulsion. Specific preferred examples of such an anion include halogen ion, nitric acid ion, perchloric acid ion, tetrafluoroboric acid ion, hexafluorophosphoric acid ion, tetraphenylboric acid ion, hexafluorosilicic acid ion, and trifluoromethanesulfonic acid ion. However, anions having strong coordination properties such as cyano ion, thiocyano ion, nitrous acid ion and oxalic acid ion undergo exchange reaction with the ligands in the complex of the present invention and thus are probably not able to maintain the composition and structure of the complex of the present invention. Accordingly, these anions are not desirable.
The synthesis of the complexes of the present invention can be accomplished by some methods. Referring to [Ru(py)6]2+ (in which py represents pyridine) for example, a synthesis method is described in J. M. Chem. Soc., 101 (1979) 4906-4917. Referring to ruthenium complexes, Coord. Chem. Rev., 84 (1988) 85-277 is a well-compiled introduction. Many complexes can be synthesized on the basis of these references.
It is desirable that each of the complexes be incorporated into silver halide grains by direct addition to a reaction solution at the step of forming silver halide grains, or by addition to a solution for grain-forming reaction via the addition to an aqueous halide solution or another solution for forming silver halide grains. Also, the combination of these methods may be adopted for doping silver halide grains.
In order to dope the silver halide grains with the complexes of the present invention, the complexes may be uniformly distributed inside the grains. Alternatively, as disclosed in JP-A-4-208936, JP-A-2-125245 and JP-A-3-188437, the complexes may be localized to have a higher concentration in the grain surface layer. Further alternatively, the silver halide grains may be doped with the complexes only thereinside but provided with an undoped layer on the surface thereof. In the present invention, the silver halide grains are preferably doped with the complexes in the surface layer thereof. In another way as disclosed in U.S. Pat. Nos. 5,252,451 and 5,256,530, the grain surface phase may be modified by physically ripening with doped fine grains. In still another way, fine grains doped with a complex are prepared, they are added to an emulsion and the resulting emulsion is subjected to physical ripening, thereby doping the silver halide grains with the complex. The aforementioned ways may be adopted in combination.
The suitable amount of each of the complexes used as dopant of the present invention is from 1xc3x9710xe2x88x929 to 1xc3x9710xe2x88x922 mols, preferably from 1xc3x9710xe2x88x927 to 1xc3x9710xe2x88x923 mols, per mol of silver halide.
The silver halide emulsion used in the present silver halide photographic material have no particular restriction as to the silver halide, but any of silver chloride, silver chlorobromide, silver bromide, silver iodochloride and silver iodobromide can be used therein. Emulsions containing bromide or iodide ions are preferred to the pure silver chloride emulsions. The silver halide grains have no particular limitation on size, but it is desirable for their size to be from 0.01 to 3 xcexcm in terms of equivalent sphere diameter. The silver halide grains may have either a regular crystal form (normal crystal grain) or an irregular crystal form, but the normal crystal grains having the regular crystal form are preferred. Examples of the regular crystal form include the crystal forms of a cube, an octahedron, a dodecahedron, a tetradecahedron, an eicosanhedron and an octatetracontahedron. Examples of the irregular crystal form include a spherical crystal form and a pebble-like crystal form. As the silver halide grains be doped with the complexes of the present invention there may be used those having a crystal form wherein two or more twin planes are present. Tabular angular or triangular grains each having two or three parallel twin planes are desirable. Further, it is preferred that the tabular grains are monodisperse grains in a grain size distribution. The preparation of monodisperse tabular grains is disclosed in JP-A-63-11928. The description of monodisperse tabular hexagonal grains is found in JP-A-63-151618. The monodisperse tabular circular grain emulsion is described in JP-A-1-131541. Further, JP-A-2-838 discloses the emulsion wherein at least 95%, based on projected area, of the total grains are tabular grains having two twin planes parallel to the major plane and the size distribution of these tabular grains is monodisperse. EP-A-0514742 discloses the tabular grain emulsion prepared in the presence of a polyalkylene oxide block polymer and thereby achieving a variation coefficient of 10% or below with respect to the grain size distribution. By using these techniques, desirable monodisperse grains of the present invention can be prepared.
There are known the tabular grains whose major planes are (100) faces and the tabular grains whose major planes are (111) faces. The silver bromide of the former type are disclosed in U.S. Pat. No. 4,063,951 and JP-A-5-281640, while the silver chloride of the former type are disclosed in EP-A-0534395 and U.S. Pat. No. 5,264,337. The tabular grains of the latter type can have various shapes wherein at least one twin plane is present, and those of silver chloride are described in U.S. Pat. Nos. 4,399,215, 4,983,508 and 5,183,732, JP-A-3-137632 and JP-A-3-116113. The dopants of the present invention can be preferably applied also to tabular grains whose major planes are (100 faces and the tabular grains whose major planes are (111) faces.
The silver halide grains may have dislocation lines on the inside. The technique of introducing dislocations into silver halide grains under careful control is disclosed in JP-A-63-220238. According to this gazette, the dislocation can be introduced by forming a particular phase having a high iodide content inside the tabular silver halide grains having an average grain diameter/grain thickness ratio of at least 2 and covering the outside with a phase lower in iodide content than the aforesaid phase having a high iodide content. The introduction of such a dislocation can produce various effects, including an increase in photographic speed, improvement in keeping quality, a rise in latent image stability and reduction in pressure mark. According to the invention of the reference cited above, the dislocations are introduced mainly in the edge part of tabular grains. On the other hand, the tabular grains having dislocations introduced in the core part are disclosed in U.S. Pat. No. 5,238,796. Further, the grains having a regular crystal form and dislocations on the inside are disclosed in JP-A-4-348337. And this gazette discloses that the dislocations can be introduced by forming epitaxides of silver chloride or silver chlorobromide on the grains having a regular crystal form and subjecting the epitaxies to physical ripening and/or halogen conversion. Into the silver halide grains according to the invention, dislocations can be introduced by the method of constituting a phase having a high iodide content as well as the method of forming epitaxies of silver chlorobromide on the grains. By the introduction of dislocations in such a way, the effects of increasing the photographic speed and decreasing the pressure mark are produced. The dislocation lines in the silver halide grains can be observed by a direct method using a transmission type electron microscope at a low temperature as described in J. F. Hamilton, xe2x80x9cPhoto. Sci. Eng.xe2x80x9d, 1967, 11, 57, and T. Shiozawa, xe2x80x9cJ. Soc. Photo. Sci. JAPANxe2x80x9d, 1972, 35, 213. In some detail, silver halide grains which have been withdrawn from the emulsion in such a manner that it is not under a pressure high enough to produce dislocation lines are placed on a mesh for electron microscopy where the specimen is then observed by a transmission method while being cooled so as to prevent itself from being damaged (print out) due to electron beam. The greater the thickness of the grains is, the more difficultly electron beam can be transmitted thereby. Therefore, a high voltage type (200 kV or higher per 0.25 xcexcm thickness) electron microscope is preferably used to make a sharper observation. From the photograph of grains thus obtained can be determined the position and number of dislocation lines on each of grains as viewed perpendicularly to the major plane. The present invention can achieve its effects when at least 50% of the total silver halide grains are grains in which at least 10 dislocation lines per grain are present.
The preparation of silver halide emulsions has no particular restrictions on additives used from the grain formation step till the coating step. For the purpose of promoting the crystal growth in the crystal-forming step or achieving effective chemical sensitization at the time of grain formation and/or chemical sensitization, silver halide solvents can be utilized. As preferred silver halide solvents, it is possible to use water-soluble thiocyanates, ammonia, thioethers and thioureas. More specifically, the thiocyanates disclosed in U.S. Pat. Nos. 2,222,264, 2,448,534 and 3,320,069, ammonia, the thioether compounds disclosed in U.S. Pat. Nos. 3,271,157, 3,574,628, 3,704,130, 4,297,439 and 4,276,347, the thion compounds disclosed in JP-A-53-144319, JP-A-53-82408 and JP-A-55-77737, the amine compounds disclosed in JP-A-54-100717, the thiourea derivatives disclosed in JP-A-55-2982, the imidazoles disclosed in JP-A-54-100717 and the substituted mercaptotetrazoles disclosed in JP-A-57-202531 can be recited as usable silver halide solvents.
The silver halide emulsions used in the invention has no particular restrictions on their preparation methods. In general, aqueous silver salt and halide solutions are added to a reaction solution containing an aqueous gelatin solution with efficient agitation. The methods usable therein are described in, e.g., P. Glafkides, Chimie et Physique Photographique, Paul Montel (1967), G. F. Duffin, Photographic Emulsion Chemistry, The Focal Press (1966), V. L. Zelikman, et al., Making and Coating Photographic Emulsion, The Focal Press (1964). More specifically, the emulsions may be prepared by any of acid, neutral and ammoniacal methods, and the methods employed for reacting a water-soluble silver salt with a water-soluble halide may be any of a single jet method, a double jet method and a combination thereof. Further, the so-called controlled double jet method, wherein the pAg of the liquid phase in which silver halide grains to be precipitated is maintained constant, may be employed. In addition, it is also desirable that the emulsion grains be made to grow at the highest speed under the critical supersaturation limit by the use of the method of altering the addition speeds of aqueous silver nitrate and alkali halide solutions in proportion to the grain growth speed (as disclosed in U.K. Patent 1,535,016, JP-B-48-36890 and JP-B-52-16364) or the method of changing the concentrations of aqueous solutions (as disclosed in U.S. Pat. No. 4,242,445 and JP-A-55-158124). These methods can be employed to advantage, because they cause no renucleation and ensure uniform growth of silver halide grains.
In another method which can be used to advantage, previously prepared fine grains are added to a reaction vessel instead of adding a silver salt solution and a halide solution to a reaction vessel, thereby causing nucleation and/or grain growth to prepare silver halide grains. The techniques concerning this method are disclosed in JP-A-1-183644, JP-A-1-183645, JP-A-2-44335, JP-A-2-43534, JP-A-2-43535 and U.S. Pat. No. 4,879,208. According to this method, the halogen ion distribution inside the emulsion grains can be uniform throughout to provide desirable photographic characteristics. On the other hand, emulsion grains having various structures can be used in the invention, too. For instance, the grains constituted of the inner part (core part) and the outside thereof (shell part), or the grains having the so-called core/shell double-layered structure, the grains having a triple-layered structure (disclosed in JP-A-60-222844) and the grains having a multi-layer structure can be used. In a case where the emulsion grains are formed so as to have an internal structure, the internal structure may be not only the wrapped-in structure as described above but also the so-called joined structure as disclosed in JP-A-58-108526, JP-A-59-16254, JP-A-59-133540, JP-A-B-24772 and EP-A2-0199290. Specifically, each host crystal joins crystallites differing therefrom in composition at its edge(s), corner(s) or face(s), and the crystallites are made to grow on the joined sites(s) to form a crystal having a joined structure. In forming such crystals joined, the host crystal may have a uniform halide composition or a core/shell structure. In the case of forming a joined structure, though crystals of silver halide can be joined together as a matter of course, another silver salt compound having a structure other than the rock salt structure, such as silver thiocyanate or silver carbonate, may also be used so long as it can attain an epitaxic growth on silver halide crystals.
In the case of silver iodobromide grains having those structures, e.g., a core/shell structure, the iodide content may be high in the core part and low in the shell part, or vice versa. As the silver iodobromide grains having a joined structure, the iodide content may be high in the host crystal and relatively low in the crystal joined to the host crystal, or vice versa. When the grains have an internal structure as mentioned above, the boundary between the parts differing in halide composition may have a clear interface, or may be rendered obscure by forming mixed crystals depending on the difference in halide composition. Also, a continuous change in structure may occur in the boundary region. Further, the silver halide emulsions used in the invention may undergo the treatment for rounding the emulsion grains (as disclosed in EP-B1-0096727 or EP-B1-0064412) or modifying the grain surface (as disclosed in German Patent 2306447 C2 or JP-A-60-221320). Although the invention prefers surface latent image-type silver halide emulsions, it is also possible to use an internal latent image type silver halide emulsion, provided that the developer or developing condition is chosen properly, as disclosed in JP-A-59-133542. In addition, a shallow internal latent image-type emulsion which is covered with a thin shell can be employed depending on the intended use.
In general, the silver halide emulsions are spectrally sensitized. Spectral sensitizing dyes usually employed therefor are methine dyes, including cyanide dyes, merocyanine dyes, composite cyanine dyes, composite merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, and hemioxonol dyes. Any rings usually present in cyanine dyes can be the basic heterocyclic rings of these dyes. Suitable examples of a basic heterocyclic ring include pyrroline, oxazoline, thiazoline, pyrrole, oxazole, thiazole, selenazole, imidazole, tetrazole and pyridine rings. In addition, rings formed by condensing together a hetero ring as described above and an alicyclic hydrocarbon ring, and rings formed by condensing together a hetero ring as described above and an aromatic hydrocarbon ring can also be utilized. Examples of such a condensed ring include indolenine, benzindolenine, indole, benzoxazole, naphthoxazole, benzothiazole, naphthothiazole, benzoselenazole, benzimidazole and quinoline rings. Each of these rings may have a substituent group on any of carbon atoms as the constituent atoms thereof. The merocyanine and composite merocyanine dyes can contain 5- or 6-membered heterocyclic rings, such as pyrazoline-5-one, thiohydantoin, 2-thioxazolidine-2,4-dione, thiazolidine-2,4-dione, rhodanine and thiobarbituric acid rings, as ketomethylene structure-containing rings.
The suitable amount of sensitizing dyes added is from 0.001 to 100 millimols, preferably from 0.01 to 10 millimols, per mol of silver halide. It is desirable for the sensitizing dyes to be added during chemical sensitization or before chemical sensitization (e.g., at the time of grain formation or physical ripening).
In the present invention, the sensitivity to light of the wavelengths at which the chemically sensitized silver halide grains show their intrinsic absorption (namely the intrinsic sensitivity) is improved. More specifically, a decrease in the sensitivity to light of wavelengths longer than about 450 mn which is attributable to the adsorption of spectral sensitizing dyes to the surface of silver halide grains, namely the intrinsic desensitization due to sensitizing dyes, can be lessened by the doping with any of the complexes of the present invention. In other words, besides the effect of increasing the intrinsic sensitivity of silver halide, the present invention has a beneficial effect upon the prevention of the intrinsic desensitization due to sensitizing dyes.
To silver halide emulsions may be added dyes which, although they themselves do not spectrally sensitize silver halide emulsions, or materials which, although they do not absorb light in the visible region, can exhibit supersensitizing effect in combination with a certain sensitizing dye. Examples of such dyes or materials include aminostilbene compounds substituted by nitrogen-containing heterocyclic groups (disclosed in U.S. Pat. Nos. 2,933,390 and 3,635,721), aromatic organic acid-formaldehyde condensates (disclosed in U.S. Pat. No 3,743,510), cadmium salts and azaindene compounds. The combinations of spectral sensitizing dyes with the dyes or materials as described above are disclosed in U.S. Pat. Nos. 3,615,613, 3,615,641, 3,617,295 and 3,635,721.
In general, the silver halide emulsions are used after undergoing chemical sensitization. For chemical sensitization, chalcogen sensitization (including sulfur sensitization, selenium sensitization, and tellurium sensitization), noble metal sensitization (including gold sensitization) and reduction sensitization can be employed individually or as a combination of at least two thereof. In the present invention, chemical sensitization involving sulfur sensitization and gold-sulfur sensitization in combination is preferably used. Selenium sensitization or tellurium sensitization also is preferably used. In sulfur sensitization, labile sulfur compounds are used as sensitizer. Examples of such labile sulfur compounds are described in P. Glafkides, Chimie et Physique Photographique, 5th ed., Paul Montel (1087), Research Disclosure vol. 307, No. 307105, T. H. James, The Theory of The Photographic Process, 4th ed., Macmillan (1977) and H. Frieser, Die Grxc3xclagender Photographischen Prozess mit Silver-Halogeniden, Akademische Verlags-geselbshaft (1968). Examples of suitable sulfur sensitizers which can be used include thiosulfates (such as sodium thiosulfate and p-toluenethiosulfate), thioureas (such as diphenylthiourea, triethylthiourea, N-ethyl-Nxe2x80x2-(4-methyl-2-thiazolyl)thiourea and carboxymethyltrimethylthio-urea), thioamides (such as thioacetamide and N-phenylthioacetamide), rhodanines (such as rhodanine, N-ethylrhodanine, 5-benzylidenerhodanine, 5-benzylidene-N-ethylrhodanine and diethylrhodanine), phosphine sulfides (such as trimethylphosphine sulfide), thiohydrantoins, 4-oxo-oxazolidine-2-thiones, dipolysulfides (such as dimorphiline disulfide, cystine and hexathiocane-thione), mercapto compounds (such as cysteine), polythionates and elemental sulfur. Also, active gelatins can be utilized as sulfur sensitizer.
In selenium sensitization, labile selenium compounds are used as sensitizer. The labile selenium compounds for such a purpose are disclosed in JP-B-43-13489, JP-B-44-15748, JP-A-4-25832, JP-A-4-109240, JP-A-4-271341 and JP-A-5-40324. Examples of suitable selenium sensitizer which can be used include colloidal metallic selenium, selenoureas (such as N,N-dimethylselenourea, trifluoromethylcarbonyl-trimethyl-selenourea and acetyl-trimethylselenourea), selenoamides (such as selenoacetamide and N,N-trimethylselenourea), selenoamides (such as selenoacetamide and N,N-dimethylphenylselenamide), phosphine selenides (such as triphenylphosphine selenide and pentafluorophenyl-triphenylphosphine selenide), selenophosphates (such as tri-p-tolylsenenophosphate and tri-n-butylselenophosphate), selenoketones (such as selenobenzophenone), isoselenocuanates, selenocarboxylic acids, selenoesters and diacylselenides. In addition, moderately stable selenium compounds (as disclosed in JP-B-46-4553 and JP-B-52-34492), including selenious acid, potassium selenocyanate, selenazoles and selenides, can also be utilized as selenium sensitizers.
In tellurium sensitization, labile tellurium compounds are used as sensitizer. The labile tellurium compounds for such a purpose are disclosed in Canadian Patent 800,958, U.K. Patents 1,295,462 and 1,396,696, JP-A-4-204640, JP-A-4-271341, JP-A-4-333043 and JP-A-4-303157. Examples of suitable tellurium sensitizers which can be used include telluroureas (such as tetramethyl-tellurourea, N,Nxe2x80x2-dimethylethylenetellurourea and N,Nxe2x80x2-diphenylethylenetellurourea), phosphine tellurides (such as butyldiisopropylphosphine telluride, tributyl-phosphine telluride, tributoxyphosphine telluride and ethoxydiphenylphosphine telluride), diacyl (di) (tellurides (such as bis(diphenylcarbamoyl) ditelluride, bis(N-phenyl-N-methylcarbamoyl) ditelluride and bis(ethoxycarbonyl) telluride), isotellurocyanates (such as allyl-isotellurocyanate), telluroketones (such as telluroacetone and telluroacetophenone), telluroamides (such as telluroacetamide and N,N-dimethyltellurobenzamide), tellurohydrazides (such as N,Nxe2x80x2,Nxe2x80x2-trimethyl-tellurobenzohydrazide), telluroesters (such as t-butyl-t-hexytelluroester), colloidal tellurium, (di)tellurides and other tellurium compounds (such as potassium telluride and sodium telluropentathionate).
In noble metal sensitization, the salts of noble metals, such as gold, platinum, palladium and iridium, are used as sensitizer. The noble metal salts for such a purpose are described in, e.g., P. Glafkides, Chimie et Physique Photographique, 5th ed., Paul Montel (1087), and Research Disclosure vol. 307, No. 307105. In particular, gold sensitization is preferred. Examples of gold compounds suitable for gold sensitization include chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide and gold selenide. In addition, the gold compounds disclosed in U.S. Pat. Nos. 2,642,361, 5,049,484 and 5,049,485 can also be used as gold sensitizer.
In reduction sensitization, reducing compounds are used as sensitizer. The reducing compounds for such a purpose are described in, e.g., P. Glafkides, Chimie et Physique Photographique, 5th ed., Paul Montel (1087), and Research Disclosure vol. 307, No. 307105. Examples of suitable reduction sensitizers which can be used include aminoiminomethanesulfinic acid (thiourea dioxide), borane compounds (such as dimethylamine borane), hydrazine compounds (such as hydrazine and p-tolylhydrazine), polyamine compounds (such as diethylenetriamine and triethylenetriamine), stannous chloride, silane compounds, reductones (such as ascorbic acid), sulfites, aldehyde compound and hydrogen. In addition, reduction sensitization can be carried out in an atmosphere of high pH or excess silver ions (the so-called silver ripening).
Two or more kinds of chemical sensitization may be carried out in combination. In particular, the combination of chalcogen sensitization and gold sensitization is preferred over the others. Further, it is desirable that the reduction sensitization be carried out in the step of forming silver halide grains. The amount of each sensitizer used is generally determined depending on what type of silver halide grains are sensitized and what condition is adopted for the chemical sensitization. Specifically, the amount of a chalcogen sensitizer used is generally from 10xe2x88x928 to 10xe2x88x922 mols, preferably from 10xe2x88x927 to 5xc3x9710xe2x88x923 mols, per mol of silver halide. The amount of a noble metal sensitizer used is preferably from 10xe2x88x927 to 10xe2x88x922 mols per mol of silver halide. As to the conditions for chemical sensitization, there are no particular restrictions. However, it is desirable that the pAg be from 6 to 11, preferably from 7 to 10, the pH be from 4 to 10 and the temperature be from 40xc2x0 C. to 95xc2x0 C., preferably from 45xc2x0 C. to 85xc2x0 C.
The silver halide emulsions can contain a wide variety of compounds for purpose of preventing fogging or stabilizing photographic properties during production, storage or photographic processing of the photographic material. Examples of compounds usable for the foregoing purposes include azoles (such as benzothiazolium salts, nitroindazoles, triazoles, benzotriazoles, imidazoles and benzimidazoles (especially those substituted with nitro groups or halogen atoms)), heterocyclic mercapto compounds (such as mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, mercaptotetrazoles (especially 1-phenyl-5-mercaptotetrazole) and mercaptopyrimidines), the above-recited heterocyclic mercapto compounds further containing a water-soluble group, such as a carboxyl or sulfo group, thioketo compounds (such as oxazolinethione), azaindene compounds (such as tetraazaindenes (especially 1,2,3a,7-tetraazaindenes substituted with a hydroxyl group at the 4-position)), benzenethiosulfonic acids and benzenesulfinic acid. In general, these compounds are known as antifoggants or stabilizers.
The appropriate time for addition of such an antifoggant or stabilizer is generally after chemical sensitization. However, the time for addition may be chosen from any stages during or before chemical sensitization. Specifically, the antifoggants or stabilizers may be added during the addition of a silver salt solution in the process of forming silver halide emulsion grains, or during the period from the conclusion of addition of a silver salt solution to the beginning of chemical sensitization, or during chemical sensitization (preferably during the first half of chemical sensitization, more preferably during the period from the beginning of chemical sensitization to the time corresponding to one fifth of chemical sensitization time).
The present silver halide photographic materials have no particular restrictions as to their layer structures. When they are color photographic materials, however, they have a multi-layer structure for recording blue light, green light and red light separately. Further, each silver halide emulsion layer may be constituted of two layers, a high speed layer and a low speed layer. Examples of a practical layer structure (1) to (6) are given below:
(1) BH/BL/GH/GL/RH/RL/S;
(2) BH/BM/BL/GH/GM/GL/RH/RM/RL/S;
(3) BH/BL/GH/RH/GL/RL/S;
(4) BH/GH/RH/BL/GL/RL/3;
(5) BH/BL/CL/GH/GL/RH/RL/S; and
(6) BH/BL/GH/GL/CL/RH/RL/S
Therein, B stands for a blue-sensitive layer, G for a green-sensitive layer, R for a red-sensitive layer, H for a highest speed layer, M for a medium speed layer, L for a low speed layer, S for a support, and CL for an interlayer effect-providing layer. Light-sensitive layers, such as a protective layer, a filter layer, an interlayer, an anti-halation layer and a subbing layer, are omitted from the foregoing representation of layer structures. Further, the arranging order or high-speed and low-speed layers having the same color sensitivity may be reversed. The layer structure (3) is described in U.S. Pat. No. 4,184,876. The layer structure (4) is described in Research Disclosure, vol. 225, No. 22534, JP-A-59-177551 and JP-A-59-177552. The layer structures (5) and (6) are described in JP-A-61-34541. Of these layer structures, the layer structures (1), (2) and (4) are preferred over the others. Besides color photographic materials, the silver halide photographic materials of the invention can be applied to X-ray photographic materials, sensitive materials for black and white photography, sensitive materials for platemaking, and photographic printing paper.
For various additives usable in the silver halide emulsions (e.g., binders, chemical sensitizers, spectral sensitizers, stabilizers, gelatin, hardeners, surfactants, antistatic agents, polymer latexes, matting agents, color couplers, ultraviolet absorbents, discoloration inhibitors, dyes), supports usable in the photographic materials and processing methods applicable to the photographic materials (e.g., coating methods, exposure methods, development-processing methods), the descriptions in Research Disclosure, vol. 176, No. 17643 (abbreviated as xe2x80x9cRD-17643xe2x80x9d), vol. 187, No. 18716 (abbreviated as xe2x80x9cRD-18716xe2x80x9d) and vol. 225, No. 22534 (abbreviated as xe2x80x9cRD-22534xe2x80x9d) can be reffered to. The locations where the additives are described in each of those references are listed below.
As gelatin hardeners there are preferably used active halogen compounds (such as 2,4-dichloro-6-hydroxy-1,3,5-triazine and sodium salts thereof) and active vinyl compounds (such as 1,3-bisvinylsulfonyl-2-propanol, 1,2-bis(vinylsulfonylacetamide)ethane and vinyl polymer having vinylsulfonyl group in its chain) because they can rapidly harden hydrophilic colloids such as gelatin to provide stable photographic properties. Also, N-carbamoyl-pyridinium salts (such as (1-morpholinocarbonyl-3-pyridinio)ethanesulfonate) or haloamidinium salts (such as 1-(1-chloro-1-pyridinomethylene)pyrrolidinium-2-naphthalenesulfonate) can rapidly harden hydrophilic colloids and therefore are preferred.
The color photographic materials of the present invention can be processed using the general methods described in Research Disclosure, vol. 176, No. 17643 and ibid, vol. 187, No. 18716. Specifically, the color photographic materials are subjected sequentially to development processing, bleach-fix processing or fixation processing, and washing or stabilization processing. In the washing step, a counter-current washing method using at least two tanks is generally adopted to effect a water saving. As a typical example of stabilization processing which can take the place of washing processing, the multistage counter-current stabilization processing as disclosed in JP-A-57-8543 can be exemplified.